The present invention relates in general to blocks including pavers, erosion control blocks, patio blocks, and other related types of blocks, and more particularly to interlocking blocks that are formed with a mold at the installation site.
The prior art is replete with the disclosure of many blocks which are interconnected together to from a mat or matrix of blocks to prevent soil erosion as a result of water, wind, traffic, etc. Various blocks can be interconnected by ropes, cables, wires, geofabrics, and many other types of mechanisms to prevent the blocks or groups of blocks from substantial lateral movement. A recent trend is to fabricate blocks that are interlocked by the use of an arm extension of one block interlocked in a socket opening of an adjacent block. This type of block prevents substantial horizontal movement without the necessity of cables or ropes threaded therethrough, or direct attachment to a geofabric. Such type of blocks are disclosed in U.S. Pat. No. 5,035,532 by Gargollo; U.S. Pat. No. 5,429,451 by Pettee, Jr.; U.S. Pat. No. 5,556,228 by Smith and U.S. Pat. No. 5,775,837 by Schneider. While these types of erosion control blocks function very well in preventing erosion of the soil at the installation site, the fabrication and installation of the same is very labor intensive.
Many of the foregoing interlocking blocks, as well as non-interlocking blocks, are fabricated by block plant equipment. Such type of equipment constitutes a large and expensive machine which utilizes a reusable mold to stamp the blocks from xe2x80x9cgreenxe2x80x9d concrete. The blocks must then be manually stacked on a pallet and moved to a location for allowing the concrete to set and cure. Then, the skid of blocks must be loaded on a truck or rail system and transported to the installation site. At the installation site, the skid of blocks must be unloaded by motorized equipment and then manually installed by workmen who must lift each block which can weigh up to 80 pounds, and lower it in an interlocking relationship with other installed locks. In other situations which may involve both interlocking and noninterlocking blocks, ropes or cables can be manually threaded through the installed blocks to provide additional containment. It is a common practice to utilize ropes threaded through interlock blocks to provide a mat of blocks which can be lifted by a crane and lowered at the installation site. Blocks fabricated for use with cable conduits therethrough are more expensive to fabricate as a tubular member must be set within the concrete block to form the channel.
Another technique for fabricating or casting a block is by the use of stamped dry concrete mix. This process is designed to be used for an off-site manufacturing plant. The blocks are formed by a machine which inserts loose dry mix concrete into a mold and then stamps and vibrates the dry mix until the block is formed. The blocks are then removed and allowed to cure. After the curing process, the blocks are either readied for shipment, or are then placed onto a lacing table and made into a matrix section at the plant. One of the disadvantages to this process is that the blocks cannot be made on site, and the process requires that the blocks be shipped to the site. The cost of the block is then greatly affected by trucking/shipping costs, and the proximity of the block plant to the project location.
If the project is located in an area that would make it unprofitable due to shipping expense, a local plant must be found. If such a plant is located near the project, it is necessary then to pay another manufacturer to produce the block, which is necessarily more costly than producing it at one""s own plant. Another consideration is that the nearby manufacturer may have a machine which is incompatible with the mold of the block to be made, and the cost of a new mold to be used for the particular machine increases the cost per block made. These molds, depending on the machine manufacturer and the shape of block mold, may cost in the area of $30,000 to $40,000. In addition, the useful life of the mold itself must be considered since the output expectancy of each mold is limited to 600,000-800,000 square feet of block coverage.
Another method utilized in fabricating blocks is a wet cast technique. This method is used to produce blocks at the installation site, or near the project location. The manufacturing process requires each block to be poured by hand utilizing many individual molds. The molds are then vibrated to fill the voids caused by pouring inconsistencies. The wet cast concrete is then allowed to cure for a day or two, depending on the concrete mix. The blocks are then removed from the molds and placed on a pallet to complete the curing process. Once the blocks have cured, they are then individually installed at the site by hand.
If the blocks are to be made into a matrix section using cables or ropes, the forms must incorporate the use of a tube or pipe in the manufacture of the block so that a cable can be used to lace the blocks together, forming a mattress or matrix section.
The wet cast method is very labor intensive, therefore, it is cost-effective only when used on small projects. The production output is directly linked to the number of molds on one location and the length of time it takes the blocks to cure so that the molds can then be reused. If enough molds are available to produce 1,000 square feet of blocks, then 1,000 square feet can be produced every day or two, depending on the curing period. Since most blocks cover less than 2 square feet of area, it would necessitate the use of approximately 600 molds to produce 1,000 square feet per day. The approximate cost per mold is presently about $35.00, which would require a capital outlay of nearly $21,000 in order to produce the required 1,000 square feet per day. The cost per square foot of this method makes large projects cost prohibitive.
Where it is desired to prevent erosion of large waterways, channels and the like, thousands of erosion control blocks may be necessary. It can be appreciated that the cost per square foot of installed erosion control blocks is critical, it being realized that if more equipment or materials and labor is necessary, installation costs increase. Where the bidding of such type of projects is involved, it is highly advantageous to be able to provide a turn key installation at a low material and labor cost.
From the foregoing, it can be seen that a need exists for a new type of block that is both constructed and installed at the site where erosion is to be controlled. Another need exists for a new type of interlocking block that is of a one-piece design, but where three dimensional interlocking capabilities is achieved. Another need exists for a cost effective block where the mold is integral with the block itself.
In accordance with the principles and concepts of the invention, there is disclosed an interlocking erosion control block that substantially reduces the shortcomings and disadvantages of the prior art blocks. In accordance with one aspect of the invention, there is disclosed a block that utilizes a mold for forming the interlocked block, where the mold can be utilized at the installation site for fabricating the block, and where the mold thereafter remains integral with the block. In accordance with another aspect of the invention, the block is fabricated as a one-piece block with openings formed from a top surface thereof to the bottom surface by the utilization of opening members forming a part of the mold. In accordance with another aspect of the invention, the one-piece block is made interlocking by the use of a socket cavity and channel arrangement formed within the block for capturing therein the enlarged end of a connector member. The connector member is constructed of a high impact plastic having an elongate midsection with enlarged ends. The other end of the connector member is captured in a similar socket cavity and channel arrangement of a neighboring block.
The installation of the erosion control block according to one feature of the invention involves the utilization of a two-part mold, namely a mold top half and a mold bottom half which, when snap fit or otherwise locked together, provide a composite mold for pouring therein concrete, or the like. The mold halves are identical in construction. The two-part mold has molded integral therewith the opening members for forming the holes through the block, as well as the socket cavities and channel structures to provide the interlocking capabilities. In accordance with another feature, opening members can be formed as part of the mold to form the cavities of interlocking blocks of the type in which the cavities are formed in the side edge of the block, from the top surface to the bottom surface thereof.
In the installation and formation of the block, the mold bottom halves are first laid out on the ground surface that is to be protected from erosion. Then, the connectors are inserted in the mold bottom halves, with the enlarged end of each connector laid in the socket cavity and channel structure portions of the respective mold bottom halves. Next, the mold top halves are snap locked onto the mold bottom halves, thereby capturing the connector ends within the socket cavities and channel structures of the neighboring blocks. A foam or other suitable material is placed around each composite mold in the spaces between the neighboring blocks to prevent the concrete from filling the interblock spaces. A foam filler is also placed inside each block hole, it if is desired to provide vegetation growth holes in the blocks. Lastly, concrete or another heavy material is disposed in each composite mold and allowed to set. The foam filler is then removed, thereby leaving a complete mat or matrix of interlocked blocks covering the ground to be protected. Substantial costs in labor and fabrication of the blocks is thus realized.